Production of dichloroethylene using melt chlorination process

ABSTRACT

A melt chlorination process which comprises chlorinating C1 to C10 hydrocarbons and their incompletely chlorinated derivatives with a melt comprising iron chloride and alkali metal chloride(s) by dispersing the material to be chlorinated in the melt whereby said material is chlorinated by the melt, wherein certain alkali metals, proportions thereof, and process conditions are utilized. Various process parameters are controlled to provide desired product selectivity. In particular, ethylene, ethylene dichloride and/or vinyl chloride are chlorinated to selectively produce at least 50 mole percent of dichloroethylene.

' atent 1 PRODUCTION OF DICHLOROETHYLENE USING MELT CHLORINATION PROCESS Inventor: Harold Edward Bellis, Hockessin,

Del.

Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: May 6, 1971 Appl. No.: 141,013

Related [1.8. Application Data Continuation-impart of Ser. No. 740,672, June 27, 1968, abandoned.

US. Cl 260/654 R, 260/654 D, 260/656 R, 260/658 R, 260/659 R, 252/441 Int. Cl. C076 21/04 Field of Search..... 260/654 A, DIG. 42, 656 R, 260/654 R, 659 A, 659 R, 658 R, 662 A, 654

References Cited UNITED STATES PATENTS 12/1938 Reilly 260/658 1 1 Mar. 18, 1975 3,363,010 l/1968 Schwarzenbek 260/648 FOREIGN PATENTS OR APPLICATIONS 711,287 6/1965 Canada 260/659 A 857,796 12/1952 Germany 260/659 R Primary Examiner-Delbert E. Gantz Assistant Examiner-Joseph A. Boska [57] ABSTRACT A melt chlorination process which comprises chlorinating C to C hydrocarbons and their incompletely chlorinated derivatives with a melt comprising iron chloride and alkali metal chloride(s) by dispersing the material to be chlorinated in the melt whereby said material is chlorinated by the melt, wherein certain alkali metals, proportions thereof, and process conditions are utilized. Various process parameters are controlled to provide desired product selectivity. In particular, ethylene, ethylene dichloride and/or vinyl chloride are chlorinated to selectively produce at least 50 mole percent of dichloroethylene.

3 Claims, 4 Drawing Figures P UENTEDHARI 8 I975 w---MELT TO SCRUBBER CONDENSERS TO SCRUBBER CONDENSERS MELT ZONE B INVENTOR HAROLD EDWARD BELLIS BY 9 y, MIR

ATTORNEY PRODUCTION OF DICIILOROETIIYLENE USING MELT CHLORINATION PROCESS CROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part of Ser. No. 740,672, filed June 27, 1968 now abandoned.

BACKGROUND OF THE INVENTION Many methods have been proposed in the prior art for randomly or selectively producing chlorinated hydrocarbons from hydrocarbons and/or chlorohydrocarbons in processes involving modified Deacon-type chlorination procedures. In processes of this character, oxygen, the hydrocarbon and/or chlorohydrocarbon to be chlorinated, and chlorine or HCl as the chlorinating agent, are brought into contact at elevated temperatures with a' metal halide catalyst, usually a copper chloride-containing catalyst. Where I-ICl is utilized as the feed material, it is believed that a preliminary oxidation of the HCl takes place resulting in the formation of water and elemental chlorine. The chlorine produced then reacts with the hydrocarbon and/or chlorohydrocarbon feed to produce further quantities of HCl and a chlorinated derivative of the feed material. When chlorine is utilized as the chlorinating agent, it is believed that an initial chlorination of the hydrocarbon and/or chlorohydrocarbon takes place which generates HCl. The I'ICl thus generated is converted by the conventional Deacon reaction to chlorine and water.

In recent years considerable emphasis has been laid on fluid bed processes for conducting such oxychlorination procedures since the reactions involved are highly exothermic and the removal of heat usually becomes a problem of considerable moment. In conducting fluidized bed oxychlorination procedures of this type, however, many difficulties are encountered. For example, in some instances the fluidized bed does not provide sufficient contact with the initial feed to produce complete chlorination or high yields of substitutive chlorination. Also, the fluidized bed becomes hard to handle in high temperature chlorination procedures. Consequently, many methods have been devised for providing adequate cooling ofthe fluidized bed catalyst particles employed during reaction. Various carriers have been tested to determine the best materials from the standpoint of thermal conductivity, lack of attrition during fluidization, and other similar considerations in order to arrive at a material suitable for use as a support for the catalyst material employed during the chlorination reaction. Product recovery from the reaction zones without injuring the catalyst particles is also another problem encountered in this area. Many of the gas mixtures fed are highly explosive under certain conditions so that proper mixing of them is an extremely important factor. In addition, corrosion of materials of construction utilized in forming the reactors involved, and the selection of the proper size of the reactors for the purpose of providing maximum productivity are also problems. It has also been found that when conducting these processes in large reactors (two feet or more in diameter), a considerable sacrifice in overall efficiency of the process contemplated is experienced.

The commercial success of these processes is due largely to the demand for halogenated compounds containing from I to carbon atoms; however, there is a great need for improvement of these processes. For example, it would be highly desirable to reduce the contact time normally associated with fixed bed operations, while eliminating the difficulties associated with fluidized solids operation such as catalyst attrition and catalyst vaporization which appears to be more pronounced with highly active catalysts. While the moving bed solves some of these difficulties, it is not without its own particular problems such as those derived from the mechanical transportation of catalysts throughout a zone and the existance of hot spots in the catalyst bed. The heat of reaction generated on the surface of the solid permits direct oxidation of the hydrocarbon and/or chlorohydrocarbon to produce undesirable oxides of carbon.

The more active metal halide catalysts such as, copper chloride, are more volatile at required halogenation temperature and thus, it is difficult to retain the catalyst in the system and maintain the activity of the catalyst mass over an extended period of time. In such systems the volatilized catalyst must be recovered by condensation or other troublesome methods and returned in a supported state to the reaction zone. Thus, the economics of operating with fluidized catalysts is poor in spite of the fact that such a system provides better temperature control and higher yield of product for a given period of operation.

Therefore, it is readily apparent that a new chlorination process is needed which overcomes the above difficulties by providing a more economic and commercially feasible chlorination process. Additionally. a better chlorination process is desired to provide improved contact between the hydrocarbon and/or chlorohydrocarbon and chlorinating agents in conjunction with good temperature control of the reaction zone. Furthermore, a selective chlorination process (i.e.. a process that produces predominantly one specific chlorinated product in high yields) is in great demand throughout the industry.

SUMMARY OF THE INVENTION This invention relates to a chlorination process which comprises chlorinating a material selected from the group consisting of ethylene, ethylene dichloride, vinyl chloride and mixtures thereof to produce a chlorinated product which contains at least 50 mole percent of dichloroethylene, in a reactionzone, which is essentially free of elemental chlorine, at a temperature within the range of from 200-450C., by means of a melt comprising iron chloride and alkali metal chloride(s) by dispersing the material to be chlorinated in the melt, the melt being the continuous phase, whereby said material is chlorinated by the melt; withdrawing a gaseous effluent from the reaction zone which contains unre acted starting material and the resulting chlorinated hydrocarbon products and recovering the chlorinated hydrocarbon products from the effluent as the products of the process; and regenerating the melt with a regenerating system selected from the group consisting of a chlorine-containing gas and a combination of an oxygen-containing gas and hydrogen chloride, wherein:

a. the alkali metal chloride is selected from the group consisting of sodium chloride, potassium chloride, a mixture thereof, a mixture of sodium chloride and no more than 20 mole percent lithium chloride, a mixture of potassium chloride and no more than 20 mole percent lithium chloride, and a mixture of sodium chloride, potassium chloride and no more than 20 mole percent lithium chloride;

b. the mole ratio of alkali metal chloride(s) to iron chloride is from about 0.521 to about 2:1; and

c. 60-90 mole percent of the iron chloride is maintained as ferric chloride.

BRIEF DESCRIPTION OF THE DRAWING For a more complete understanding of the invention reference is made to the accompanying drawing which illustrates suitable apparatus for carrying out the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred process of this invention involves chlorinating ethylene, ethylene dichloride, vinyl chloride or mixtures thereof, to produce high yields of dichloroethylene by contacting the ethylene, ethylene dichloride, vinyl chloride or mixtures thereof with the abovedescribed melt. In addition, the process of this invention is equally applicable to the chlorination of these C materials together with minor amounts of many other C to C hydrocarbons and/or their incompletely chlorinated derivatives, and more specifically, to C to C unsaturated hydrocarbons and their chlorinated derivatives. However, since the desired ultimate product must contain at least 50 mole percent of dichlorethylene, the minor amounts of other materials to be chlorinated must be such as not to change this chlorinated product requirement.

Since ethylene is one of the preferred starting materials, the discussion throughout the specification is directed to the chlorination of ethylene, without intending to limit the scope of this invention to ethylene.

It is pointed out that when chlorinating ethylene, the preferred process of this invention effects a high selectivity toward dichloroethylene. The terminology high selectivity" is intended to designate that at least 50 mole percent of the chlorinated product is dichloroethylene (DCE), with a preferred selectivity being at least 70 percent DCE. 1

The preferred process of this invention is also directed to producing high yields of chlorinated hydrocarbons. The terminology high yields means that a high percentage (at least 70 percent) of the starting material is converted to chlorinated hydrocarbons, with the yield losses being represented by C0, C and any other oxygen-containing by-products. More specifically high yields of dichloroethylene are desired with the yield losses being C0, C0 and any other oxygen-containing by-products. In order to achieve high yields, the melt composition (e.g., KCl, etc.), temperature, HCl partial pressure and oxide content must be optimized within the teachings of this invention.

Generally as ethylene is chlorinated, with the progressive addition of chlorine and splitting out of HCl, the chlorination products are as follows: ethylene dichloride (l,2-dichloroethane), vinyl chloride, 1,1,2- trichloroethane, dichloroethylene (DCE), tetrachloroethane, trichloroethylene, pentachloroethane, perchloroethylene, and hexachloroethane. The employment of the various process parameters of this invention results in a high selectivity of product to at least 50 percent dichloroethylene in the preferred embodiment, with smaller amounts of the incompletely chlorinated derivatives (e.g., ethylene dichloride, vinyl chloride, and

1,1,2-trichloroethane) being produced; very minor amounts of the more completely chlorinated derivatives (e.g., tetrachloroethan trichloroethylene, pentachloroethane, perchloroethylene and hexachloroethane) may also be produced.

The chlorination process of this invention involves the use of a particular melt which contains certain metal chlorides in critical proportionate amounts to produce the desired selectivity of product. The essential components of the melt composition are ferric chloride and alkali metal chloride(s). The ferric chloride is considered to have at least two functions; it acts as a chlorinating agent and also as a dehydrohalogenating agent. The function of the alkali metal chloride(s) is to reduce the vapor pressure of ferric chloride and also to reduce the chlorinating power of the ferric chloride in order that the chlorination product can be stopped selectively, for example, in the case of ethylene, at dichloroethylene. The alkali metal chloride also is necessary to produce a melt and to moderate the dehydrohalogenating (HCI cracking) reaction.

Since ferric chloride acts as the chlorinating agent,

.there must be some ferric chloride present in the melt at all times. Therefore, one of the essential features of this invention is that about 60 mole percent of the iron chloride be maintained'as ferric chloride.

Ideally, it is desirable to have only FeCl present since this is the chlorinating agent. However, ferric chloride a solid which melts at 300C. and then sublimes at almost the same temperature. has an impractical operating range as the sole composition in a melt. Therefore, an alkali metal chlorid is added to form a complex salt (MFeCh) with FeCl to thereby extend the operating range of the melt. Sodium chloride, for example, and FeCl, form a known compound, NaFeFh, which melts at about C. and has a low vapor pressure at temperatures even about 400C. It has been observed that the potassium complex salt (KFeCh) forms a more stable complex than NaFeCl and LiFeCh. Thus, the presence of the alkali metal chloride(s) moderates the chlorinating ability of the melt. While not intending to be boundby any particular theory, the chlorination reaction taking place in the melt is interpreted as follows:

Ml-eCl MCH-FeCl +Cl. However, it is'not entirely certain whether the actual chlorination reaction occurs in accordance with the 1 above equation. For example, chlorine radicals may emanate and go directly from the FeCl to the hydrocarbon. On the other hand, some free chlorine radicals may randomly contact the hydrocarbon and chlorinate the hydrocarbon. Thus, it is to be understood that it is the combination of all the components acting together in the melt that does the chlorinating.

The above reaction is a reversible reaction. By adding chlorine (C1 2Cl-) to a melt containing MCI and FeCl the MFeCL; can be regenerated. Also, as the concentration of MCI is increased up to its solubility limit, the reversible reaction is driven toward the MFeCl, complex salt and this presumably lowers the concentration of chlorine free radicals. Hence, the extent of hydrocarbon chlorination is decreased. Also, since the amount of uncomplexed FeCl is reduced by adding an increased amount of MCI, the dehydrohalogenating power of the melt is reduced and this in turn favors the production of saturated chlorohydrocarbons.

The alkali chlorides (MCl) that are suitable include KC], NaCl and LiCl. The presence of these chlorides is necessary to produce a liquid phase with ferric chloride, to depress the volatility of the ferric chloride at operating temperatures and to obtain a ferric chloridecontaining melt which will have selective chlorinating power. The alkali chloride (MCl):FeCl ratio should be from 0.5:1 to 2:] in the preferred DCE process. These are the critical proportions of this invention. Below 0.5 mole alkali chloride per mole of FeCl,,, there is not enough alkali chloride to tie up the FeCl and the FeCl volatilizes out of the reactor. As the amount of MCI is increased to above 2 moles per mole of FeCl,,, the MFeCl, salt is more stable and is less able to give off the desired chlorine to chlorinate. The vapor pressure of the chlorine is diminished by too much alkali chloride and an insufficient amount of chlorination is achieved. Also, at ratios of MCl:FeCl the melting point of the melt chloride mixture is too high so that the system becomes too difficult to operate.

The broadest aspects of the invention include the use of KC], NaCl, RbCl, CsCl and mixtures thereof, in conjunction with iron chloride. The rate and degree of chlorination varies with each chloride; the activity rates are: LiCl NaCl KCl. The rate and degree of chlorina tion can be adjusted by the choice of alkali metal chloride(s) and the amount of alkali metal chloride, which must always be kept within the prescribed limits (i.e., 0.5:! to 2:1 alkali metal chloride to iron chloride). When chlorinating ethylene to produce dichloroethylene as the desired product, no more than mole percent (0-20 mole percent) of the alkali metal chloride can be LiCl. More than 20 mole percent LiCl will produce major amounts of higher chlorinated products (e.g., symmetrical tetrachloroethane). Thus, rate and degree of chlorination can be optimized by one skilled in the art in accordance with the teachings of this invention.

Alkaline earth metal chlorides (e.g., calcium and barium chlorides) may also be used in the melt, but the alkaline earth metal chlorides are not preferred since they do not adequately depress the volatility of FeCl;, as is done by the alkali chlorides. The use of the alkaline earth chlorides, however, is within the scope of this invention.

In the broad spirit of this invention, minor amounts of iron chloride may be replaced by CuCl when the higher chlorinated products are also desired (e.g., symmetrical tetrachloroethane, trichloroethylene, perchloroethylene). Thus, while CuCl may be used in the melt, it is not necessary to carry out the process of this invention.

The temperature at which the melt chlorination process of this invention is carried out is generally within the range of 200450C, The temperature range is dependent upon the metal chloride salt mixture which is utilized and the desired product. Lower temperatures may be used where lower chlorination rates are acceptable or where pressures greater than one atmosphere are utilized. The temperature range of 200-450C., in the preferred process where ethylene, ethylene dichloride, vinyl chloride or mixtures thereof are use as the starting materials, is the temperature at which a high selectivity to dichloroethylene results, i.e., at least 50 mole percent dichloroethylene. For example, when ethylene is the starting materials and sodium chloride is used as the alkali chloride metal, the temperature range of 290-350C. is preferred. If the temperature is decreased below 290C, the product mix will contain smaller amounts of dichloroethylene and larger amounts of ethylene dichloride and vinyl chloride. As the reaction temperature is increased, if the process is run above 350C. and when sodium chloride is used as the alkali metal, the product mix will contain smaller and smaller amounts of dichloroethylene and greater amounts of the higher chlorinated products (e.g., tetrachloroethane, trichloroethylene and perchloroethylene). When potassium chloride is used as the alkali metal chloride, the preferred temperature range is 350450C. to produce the high selectivity to dichloroethylene. When 20 mole percent of lithium chloride is used in the alkali metal chloride, mixture, a preferred range is 260-280C. Thus, the temperature range for the production of at least 50 mole percent dichloroethylene in 200450C.

The oxidation level of the iron chloride is critical; in the preferred process at least 60 mole percent of the iron should be maintained in the ferric (Fe-H-H state (i.e., at least 60 mole percent FeCl If less than 60 percent ofthe iron is in the ferric state, chlorination occurs but the rate of chlorination is low. In the case of ethylene, dichloroethylene is not the major product and chlorinated products, such as ethylene dichloride, are produced. The upper limit is not as critical to the extent that some type of chlorinated products are pro ducted; however, the higher oxidation levels (9ll00 percent ferric state) generally produce the higher chlorinated products, such as tetrachloroethane and perchloroethylene. The proper oxidation level must be se lected in order to obtain the desired product selectivity. Therefore, when dichloroethylene is the desired major product, the oxidation level is from 60-90 mole percent of iron in the ferric state.

The pressure employed in the chlorination process can vary considerably and be as high as 50 atmospheres. A pressure within the range of l to 10 atmosphere is preferred. The pressure utilized is restricted by materials of construction and the problems of handling the melt at the high operating temperatures ofthis invention.

The atmosphere employed in the melt and surrounding the melt, in the preferred chlorination process, is essentially free of any substantial amount of added elemental chlorine. This terminology is intended to exclude the presence or addition of free chlorine to the reaction zone for the purpose of directly chlorinating the hydrocarbon. Since this process involves using the melt itself as the chlorinator, no free elemental chlorine is required or used to directly chlorinate the hydrocarbon. However, the melt itself might give off minor amounts of elemental chlorine through decomposition of the metal chlorides. Also, free chlorine may be added to the reaction zone to regenerate the melt. However, the chlorine, even when premixed with the feed, will preferentially oxidize (chlorinate) the FeCl to FeCl rather than enter into the hydrocarbon chlorination reaction. Therefore, the terminology atmosphere essentially free of elemental chlorine is intended to permit the presence, in the reaction zone. of minor amounts of elemental chlorine which are given off by the melt, or used to regenerate, but not the presence or addition of any elemental chlorine. separate and apart from the melt, which would in fact chlorinate the hydrocarbon.

The hydrocarbons suitable for the chlorination reactions described herein include saturated aliphatics such as methane, ethane, propane, the butanes, and hydrocarbons containing up to 10 carbon atoms; unsaturated aliphatic hydrocarbons, such as ethylene, propylene, the butylenes, butadiene, isopropene and hydrocarbons containing up to about 10 carbon atoms including isomeric types; and aromatically unsaturated hydrocarbons, such as benzene, toluene, xylene, styrene, etc. Also, there incompletely chlorinated derivatives can be used. The terminology incompletely chlorinated derivatives is intended to include hydrocarbons containing at least one hydrogen atom which can be replaced by chlorine. For example, vinyl chloride, ethylene dichloride, 1,1,2-trichloroethane, symmetrical and/or unsymmetrical tetrachloroethane, chlorobenzene, etc., can be used as starting materials. Of this group, the preferred hydrocarbons are ethylene, ethylene dichloride and vinyl chloride. Additionally mixtures of all of the above-listed materials can be used as the starting materials (feed stock).

The process of this invention involves providing good contact between the hydrocarbon gas and the melt. An effective method that may be used is to disperse the gas in the body of the melt. The dispersal may be effected by forcing the gas, in the form of fine bubbles, to ascend through the melt, by any known means. Typical means include porous plate, or porous thimbles, a suitable bubbling apparatus of a sparger. A stirring apparatus may also be used. Several stages may be used, with the gas being dispersed into the melt at several different positions in the apparatus, while the melt is passed continuously from one stage to another. An essential requirement is that the hydrocarbon gas be dispersed and finely distributed throughout the melt to provide good contact between the hydrocarbon gas and the melt, and to obtain a reasonable reaction rate. The size or fineness of the bubbles also has an effect on the reaction rate. The reaction rate increases directly with an increase in the fineness of the hydrocarbon gas bubbles, an increase in the amount of agitation utilized to disperse the hydrocarbon gas in the melt, or any increased overall contact of the hydrocarbon gas with the melt. However, the scope of this invention is not intended to be limited to any particular dispersing mechanisms. Comparatively speaking, if slower reaction rates and chlorination rates can be tolerated, there is no necessity for a thorough dispersion of the hydrocarbon gas in the liquid melt as is required in the preferred embodiment of the invention.

The process of this invention can be carried out as follows: the required amounts of each metal salt, in solid form, are mixed together to obtain even distribution of the respective salts in the salt mixture. This salt mixture is added to a reaction vessel where it is heated to a temperature within the range of 200-450C. whereby a melt of the salt mixture is obtained. If any of the metal salts were melted separately, various operating problems would arise. For example, if ferric chloride were melted separately, it would vaporize and boil off (e.g., sublime at high temperatures). If the alkali metal salts were melted separately, very high temperatures would be required since they have high melting points. Therefore, by using a mixture of the metal salts, a melt or molten solution of the metal salts can be 8 readily obtained at the operating temperatures of this process.

Then ethylene (or any other suitable hydrocarbon or chlorohydrocarbon) is fed to the reaction vessel through any appropriate inlet means. lt is a matter of choice and designing skill to decide whether the ethylene enters through the side, top or bottom of the reaction vesse. It is preferred however, that the ethylene enter the reaction vessel near the bottom to give the ethylene a longer contact time with the melt. The ethylene is chlorinated and the chlorinated hydrocarbon reaction products, containing at least 50 percent dichloroethylene, begin to vaporize and rise to the top of the reaction vessel. An outlet is provided, usually at the top of the reaction vessel, where the reaction products can be drawn off; a condensation system, and possibly a scrubber system, could also be provided to recover and/or recycle any unreacted ethylene. The abovedescribed process is essentially a batch-type process; when the oxidation level of the iron chloride drops below the point where 60 percent of it is in the ferric chloride state, this batch process would not chlorinate to the desired high selectivity and-high yield of dichlo roethylene. The batch process would have to be stopped in order to regenerate the melt to at least the 60 percent ferric chloride level. A suitable batch operz1- tion can be carried out by alternatively chlorinating the hydrocarbon (e.g., ethylene), and then regenerating the melt with a chlorine-containing gas or a combination of an oxygen-containing gas and hydrogen chloride prior to the next chlorination run.

The preferred regenerating system comprises a combination of an oxygen-containing gas and hydrogen chloride. This includes the use of mixtures of an oxygen-containing gas and HCl as well as the stepwise use of an oxygen-containing gas and HCl (and vice versa). Any regenerating procedures involving the use of an oxygen-containing gas and hydrogen chloride are applicable.

The terminology a chlorine-containing gas" includes free elemental chlorine, a mixture of chlorine and oxygen, a mixture of chlorine and hydrogen chloride, and mixtures of chlorine and any other gases which are compatible with the chlorination system. The terminology an oxygen-containing gas encompasses free elemental oxygen and mixtures of oxygen and other gases which are compatible with the chlorination system. Air is an economical oxygen-containing gas which can be used.

The preferred process of this invention is a continuous process whereby the melt is continually chlorinating ethylene, being regenerated, and/or recycled. The continuous process of this invention can be operated as either a single-stage operation or a multi-stage operation. In a single-stage continuous process, one reaction vessel is used. While the chlorination is taking place and the ferric chloride is being reduced to ferrous chloride, a chlorine-containing gas or a mixture of an oxygen-containing gas and hydrogen chloride are added to regenerate the melt. Thus, the ethylene is continuously chlorinated by the melt and drawn off in high yields of dichloroethylene at the same time that the melt is being regenerated to provide the required ferric chloride to chlorinate the ethylene. If a chlorine-containing gas is added to regenerate the melt, preferably the chlorine will be supplied in a separate section or zone of the reaction vessel so that the atmosphere in the reaction zone is essentially free of any substantial amount of elemental chlorine. A typical reaction vessel might contain a central conical section for reacting the hydrocarbon with the melt and a separate side section between the conical section and the walls of the vessel for regeneration of the reduced melt.

The multi-stage continuous process requires use of two or more vessels or reaction zones. The first vessel would be the reaction vessel in which the actual chlorinating is done. The reduced melt containing ferrous chloride would then be pumped to another vessel to be oxidized and thereby regenerated to the ferric state. Into the second and any succeeding vessels is introduced a combination of an oxygen-containing gas (e.g., air) and HCl or a chlorine-containing gas. Also, any byproduct water may be removed from the melt in the regeneration zone or in a separate zone. The regenrated melt containing ferric chloride would then be recycled to the original reaction vessel to chlorinate the unchlorinated ethylene.

The chlorination reaction occurring in the reactor may be represented by the following equation (neglecting the role of MCl): H

10 FB O +FeCl Therefore, both Fe O and FeOCl are considered to be present in the melt. In order to make dichloroethylene, HCl must be eliminated from the ethylene dichloride molecule. Both F6203 and FeOCl will convert HCl to water. Consequently, the presence of Fe O (an HCl acceptor) aids splitting out HCl and converting HCi to water.

In a bath process, the Fe O is added in a specified amount to saturate the melt or it is generated in situ by oxidation of FeCl in a partially reduced melt. In a continuous process where oxidation is being carried out at all times, the melt may contain some Fe O produced by the following equation:

to occur. The saturation level generally ranges from 0.05 to percent. v

l- FeCl H C=CH HC=CH EHCl -l- FeCl 7 c1 c1 The regeneration reactions can be represented by the following equations:

temperatures, the melt spontaneously vaporizes and drives off the water so that the system is operating at its equilibrium water content, which for example, at 400C. is about 1 percent for a KCl/FeCl melt. However, when using lower temperatures, water will build up in the system. This water can be removed by transporting the melt to a separate zone where it can be effectively removed, such as by gas stripping or vacuum flashing.

The amount of oxygen absorbed by the melt is controlled by the rate of passage of the oxygen-containing gas over and through the melt in the regeneration contact zone(s), the pressure of the oxygen-containing gas, the length of the contact zone and the efficiency of the overall regeneration system. Moderate pressures generally give rapid and efficient absorption of oxygen in the melt although operations at atmospheric pres sure give satisfactory results. Air pressures between 1 and 50 atmospheres may be employed, however, the preferred range is between 1 and 10 atmospheres.

When air is utilized as the gas, absorption of from to 75 percent of the oxygen from the contacting air is readily obtainable. In general, it is not practical to attempt to remove all the oxygen from the air passing through the regeneration zone.

An alternative regeneration reaction is as follows:

2FeCl +Cl 2FeCl is believed to equilibrate with FeCl to form FeOCl as shown by the following equation:

Another ingredient which may be added to the melt is alkali fluoride. The presence of alkali fluoride in the melt increases the product selectivity to dichloroethylene. The fluoride of iron (FeF is more stable than the chloride of iron (FeCl Consequently, the addition of small amounts of fluoride tends to tie up the ferric ion and, therefore, tends to impede the chlorination reaction. The presence ofa little fluoride probably acts the same as the presence of an excess alkali chloride; it cuts down on the vapor pressure of the chlorine, makes the melt less reactive to ethylene, and reduces the amount of higher chlorinated products. The alkali fluoride may comprise up to l0 percent of the total alkali halide present in the melt. The suitable alkali fluorides are: sodium fluoride, potassium fluoride, and lithium fluoride.

It is pointed out that the process of this invention is directed to chlorinating by means of a melt (molten salts) as distinguished from chlorinating in" the melt or hiolten salt. It is the melt itself which does the chlorinating in the process of this invention and not any other liquid or gaseous additives. The process is significantly different from chlorinating with elemental chlorine because elemental chlorine gives a random product distribution whereas the process of this invention is selective and produces high yields. Chlorinating by means of a melt provides additional significant advantages ovoer the prior chlorination processes. There is a uniform temperature throughout the melt and, consequently, a uniform chlorination rate. There is no agglomeration of catalyst particles as in a fluidized bed. More complete chlorination rates are available due to the presence of massive amounts of the chlorinating composition in the melt. In short, the melt chlorination process of this invention provides a more effective means for chlorinating.

The invention is illustrated by the following examples. In the examples and elsewhere in the specification all parts, proportions and percentages of materials or EXAMPLE 1 EXAMPLE 2 This example illustrates the importance of agitation (gas dispersion) upon substitutive chlorination of ethylene using the melt described in Example 1. The same process was carried out but at a temperature of 345C. The comparison between a mechanically stirred and unstirred melt is shown in Table I.

When the melt reached the 82 percent oxidation level, the reaction was stopped by cutting off the ethylene feed. Then hydrogen chloride and oxygen were passed into the glass reactor to regenerate the melt to a 99 percent oxidation level; water was condensed as a by-product. This illustrates a step-wise regeneration procedure in a single reaction zone.

EXAMPLE Into a glass reactor containing 0.65 liter of a melt of moles LiCl and 10 moles FeCl was passed 2.2 moles of ethylene per hour. The chlorination process was operated at a temperature of 275C., at atmospheric pressure while the melt was mechanically stirred. Approximately 3 mole percent of the ethylene fed was converted to chlorohydrocarbons with about 67 percent selectivity to chloroethylenes. The results are reported in Table I. It can be seen that the use of 100 percent LiCl as the alkali produced higher chlorinated products than the desired dichloroethylene.

TABLE 1 Chlorohydrocarbon Analysis Mole Percent Oxidation 7: 7r 3% Gms/ Level ViCl EtCl DCE EDC TR] B-TRl PER TETRA HEXA min.

Ex. 1 92 1.9 14.6 46.4 7.6 9.4 0.6 11.8 7.6 0.1 2.03 81 3.8 14.3 61.7 10.2 3.9 1.1 0.6 4.2 0.2 1.94 72 3.3 16.6 60.5 10.9 3.8 0.7 0.4 3.9 0.0 1.73 63 4.0 18.1 57.6 12.1 3.5 0.7 0.4 3.7 0.0 1.50 Ex. 2 *83 1.0 6.5 66.6 9.5 10.8 0.0 3.4 2.4 0.0 81.8 "70 0.0 2.7 46.0 35.2 6.9 0.8 7.2 1.2 0.0 60.1 *66 1.1 12.8 62.3 14.9 4.4 0.6 2.4 1.6 0.0 70.2 Ex. 3 82 1.7 6.8 68.2 13.6 6.8 0.5 1.3 0.8 0.0 3.47 80 1.4 7.5 61.4 8.9 10.9 0.0 7.2 2.6 0.0 2.60 Ex. 4 97 2.3 0.5 48.4 37.9 2.2 3.3 0.2 3.1 1.4 1.05 95 2.5 1.0 69.3 21.2 2.2 1.6 0.2 0.4 0.5 0.75 89 13.2 2.3 60.1 19.6 1.6 1.3 0.6 0.3 0.4 1.45 82 21.5 2.6 53.5 16.0 1.8 1.0 0.7 0.7 0.0 1.75 EX. 5 93 0.2 24.9 l 2 7.3 5.9 0.1 59.6 3.0 1.7 0.62

' Explanation of Abbreviations: ViCl vinyl chloride EtCl ethyl chloride DCE dichloroethylene EDC ethylene dichloride TR! trichloroethylene fl-TRI 1,1,2 trichloroethane PER perchloroethylene TETRA tetrachloroethane W ..L.. ...!1 A :HEQEHQEEEEF Stirred *jUnstirred EXAMPLE 3 EXAMPLE 6 This example illustrates the effect of varying the ratio of sodium chloride to ferric chloride in accordance with the procedure used in Example 1. At a temperature of 340C, the results obtained from using a NaCllFeCl ratio of 1.1:1 and 1.3:1, respectively, are shown in Table l.

EXAMPLE 4 This example illustrates steady state chlorination of ethylene to dichloroethylenes with simultaneous regeneration of the melt with oxygen and hydrogen chloride in a zoned single reactor.

Into the glass vessel such as that illustrated in FIG. 1, containing 1.7 liters of a melt consisting of 16.2 moles (2625 grams) ferric chloride, 8.1 moles (604 grams) potassium chloride, and 8.1 moles (473 grams) sodium chloride, were passed 2.7 moles ethylene, 2.7 moles hydrogen chloride, and 0.8 mole oxygen per hour. Ethylene was fed through inlet 1 into zone A, while oxygen and hydrogen chloride were premixed and fed through inlet 2 into zone B at atmospheric pressure. The gases were disposed through porous glass frit 3. The temperature of the melt was determined with thermocouple 4 to be 335C. After steady state was achieved at an percent oxidation level, a gaseous effluent was withdrawn through scrubber 5. About 1 1 mole percent of the ethylene fed was converted to chlorohydrocarbons percent oxidation level about 60 mole percent of the with an 82 percent selectivity to chloroethylenes; 3.7 ethylene dichloride fed was converted to other chloropercent of the converted ethylene reacted to form CO hydrocarbons with about a 99 percent selectivity to and CO2, providing a product yield of 75 percent. Also, chloroethylenes. The isomeric dichloroethylenes com- 94 percent of the supplied oxygen as used (reacte prised about 87 percent of the chlorohydrocarbon fracand the HCl content of the residual HCl/water phase ti n as shown below:

was 71 weight percent. The isomeric dichloroethylenes comprised about 73 mole percent of the chlorohydro- Vinyl chloride 2.3 mole 7: carbon fraction as shown below. Dichlomethylene 869 mole 7 10 Trichloroethylene 8.5 mole 7r Perchloroethylene 1.0 mole 7: Vin I chloride 0.3 mole 7t 1,1,2-trichloroethane 0.6 mole 7: Die loroethylene 73.0 mole Sym. tetrachloroethane 0.7 mole 7t gllClLlfl'OCllLYlfnC 7.5 mole 7r Chloral .0, mole?! erc oroet y ene 0.7 mole 7: r Ethyl chloride 1.1 mole 7. 100") Ethylene dichloride 15.4 mole l 1,1,2-trichloroethane 0.7 mole 72 Sym. tetrachloroethane 0.9 mole EXAMPLE 9 Pentachloroethane V- 0.1 mole Chloral (1.3 mole ThlS example lllustrates steadystate chlorination of 100-0 mole eth lene dichloride to dichloroeth lenes with simulta y a y d neous regeneration of the melt with chlorine in an un- EXAMPLE 7 zoned single reactor.

Into the glass vessel of FIG. 2 containing 2.8 liters of This example illustrates steady state chlorlnatlon of a melt consisting f 270 moles (4380 grams) ferric ethylene dichloride to chloroethylenes with simulta- Chloride and 27 moles (1578 grams) godium Chlo neous regfmfiatiw of m oxygen and hydro ride, were passed 4.1 moles ethylene dichloride, 2.5 gen Chlonde a Zoned Smgle reactor; moles chlorine and 0.2 mole hydrogen chloride per To the Same melt and descf'bed m Example hour. The ethylene dichloride was vaporized and intro- 6 were fed moles ethylene dlchlonde moles duced through inlet 6 while the chlorine and hydrogen dmgen Chloride i mole Oxygen per hour chloride were introduced through inlet 7 at atmolleated .ethylene dlchlollde vapors were fed through 30 spheric pressure. The gases were dispersed through po- 1 Into whlle Oxygen hydmgen ch10 rous glass frit 8. The temperature of the melt was deterrlde were premixed and fed through inlet 2 into zone mined with thermocouple at 3450C after Steady B at amPSPhem pressure At 9 after Steady state state was achieved at an 81 percent oxidation level a was achieved at an 87 percent oxidation level, about 22 gaseous effluent was withdrawn through Scrubber percent of the ethylene dichloride was converted 35 About 52 mole percent of the ethylene dichloride fed to hlghgr chlorohydrocarbons wlth about a 95 percent was converted to other chlorohydrocarbons with about selectivity to chloroethylenes; 3.5% of the converted a 96 percent Selectivity to chloroethylenes The ethylene dichloride reacted to form CO and CO prodlchloroethylens comprised about 75 mole per vldlng a product yleld of 86 percent. Also, 92 percent menc ofthe Supplied Oxygen was used (reacted) and the HC! cent of the chlorohydrocarbon fraction as shown be content of the residual HCl/water phase was 91 weight percent. The isomeric dichloroethylenes comprised about 81 percent of the chlorohydrocarbon fraction as Vinyl chloride mole shown below: Dichloroethylene 75.3 mole 72 Trichloroethylene l 1.1 mole 7r Perchloroethylene 4.1 mole 1 I 1,1,2-trichloroethane 1.2 mole 7( l chlonde mole Sym. tetrachloroethane 1.9 mole Z Dlc loroethylene 80.7 mole 7a chloral Q6 mole e; Trichloroethylene 13.0 mole Perchloroethylene 2.1 mole 7c 1,1.2-trichloroethane 1.4 mole 7c gym. tetrachloroethane 1.1 mole 7r hloral 0 7 m ole '.7r. EXAMPLE 10 100.0 mole 71 This example illustrates chlorination of ethylene to dichloroethylenes with subsequent regeneration of the EXAMPLE 3 melt with oxygen and hydrogen chloride in an unzoned This example illustrates steady state chlorination of Single reaction ethylene dichloride to dichloroethylenes with simulta- Into the gla$ 5 Vessel of 3, comalnmg llters 0f neous regeneration of the melt with chlorine in a zoned a melt Consistmg 0f 15 moles (2433 grams) ferric ch10- in l r t ride and 15 moles (1119 grams) potassium chloride, To 5.5 liters of a melt consisting of 46.7 moles (7560 were Passed {Holes ethylene P hour; The ethylene grams) f ri hl rid 23,4 moles (1745 a om was fed through inlet 11 beneath vane-disc agitator l2 slum chloride and 23.4 moles (1368 grams) sodium rotating at 1200 RPM. The temperature of the meltwas chloride contained in the glass vessel of FIG. 1 were e mi th thermocouple 13. At 379C, a total of passed per hour 7.0 molesethylene dichloride and 5.2 .6 moles of ethylene was fed over a period of minmoles chlorine per hour. Ethylene dichloride vapors 65 utes. A gaseous effluent was withdrawn through scrubwere fed through inlet 1 into zone A, while chlorine ber 14. About 32 mole percent of the ethylene fed was was fed through inlet 2 into zone B at atmospheric presconverted to chlorohydrocarbons with a percent sesure. At 350C. after steady state was achieved at an 86 lectivity to chloroethylenes. The isomeric dichloroethylenes comprised about 69 mole percent of the chlorohydrocarbon fraction as shown below:

Vin l chloride 17.3 mole 7: Die loroethylene 68.8 mole 9: Trichloroethylene 3.8 mole 7c Perchloroethylene 0.4 mole Ethyl chloride 2.5 mole Ethyl dichloride 6.7 mole 1,1 ,2-trichloroethane 0.3 mole Sym. tetrachloroethane 0.1 mole 7c Pentachloroethane 0.0 mole Hexachloroethane 0,0 molg Chloral 0.1 v.molell; 100.0 mole The oxidation level of the meltwas reduced from 100 to 72 percent.

The ethylene feed was shut off and the melt was reoxidized with oxygen. At 375C., while stirring at 1200 RPM, oxygen was fed through feed 11 at the rate of 1.1 molesper hour. After feeding 1.2 moles oxygen, the melt oxidation level had been raised from 72 to 100 percent and iron oxides were found in the melt equivalent to oxygen consumed.

The oxygen feed was shut off and the melt was treated with hydrogen chloride. At 375C. while stirring at 1200 RPM, hydrogen chloride was fed through feed 11 at the rate of 2.9 moles per hour. After feeding 5.8 moles of hydrogen chloride, a total of 2.1 moles of water had distilled from the melt through scrubber 14 with complete conversion of iron oxides to iron chloride.

EXAMPLE 11 This example illustrates the chlorination of ethylene in one reactor with concurrent regeneration of the melt with hydrogen chloride and oxygen in another reactor. Melt was circulated between reactors. Products were removed separately from each reactor.

Into zone A of the glass vessel of FIG. 4, containing 2.3 liters of melt consisting of 22.5 moles (3650 grams) ferric chloride and 22.5 moles (1675 grams) potassium chloride was passed 4.9 moles of ethylene per hour. Ethylene was fed through inlet 15 into zone A while hydrogen chloride and oxygen were fed through inlet 16 into zone B. Zone B also contained 2.3 liters of melt consisting of 22.5 moles (3650 grams) ferric chloride and 22.5 moles (1675 grams) potassium chloride. Into zone B were passed 4.9 moles oxygen and 7.3 moles hydrogen chloride per hour at atmospheric pressure. Constant speed paddle agitators 17 dispersed the gases in the melt. The melt was circulated between zones A and B via gas lift pumps. 18. Thermocouples which were 6.3 mole 71.3 mole 70 Vinyl chloride Dichloroethylene In Continued Much modification and optimizing of process parameters can be carried out in addition to those described in the above examples. For example, the selective pro- .cess of producing dichloroethylene can be carried nearly or close to percent conversion by properly adjusting the temperature, oxidation level and feed rate of the process. Also, high yields (e.g., with minimum side reaction products such as CO and CO can be obtained by selecting the proper melt composition, oper-- ating at optimum temperatures and utilizing preferred feed compositions.

Many statements of theory and suggested reasons for various reactions are given throughout the specification. However, this invention is not intended to be based on any particular theory or limited to any such reasons. The theory has been given mainly to aid in understanding the processes of this invention but in no way to limit or restrict the scope of this invention except as set forth in the claims.

What is claimed is:

1. A chlorination process consisting essentially of chlorinating a material selected from the group consisting' of ethylene, ethylene dichloride, vinyl chloride and mixtures thereof to producea chlorinated product which contains at least 50 mole percent of dichloroethylene, in a reaction zone, which is essentially free of elemental chlorine at a temperature within the range of from 200450C., by means of a melt comprising iron chloride and alkali meltal chloride by dispersing the material to be chlorinated in the melt, the melt being the continuous phase, whereby said material is chlorinated by the melt; withdrawing a gaseous effluent from the reaction zone which contains unreacted starting material and the resulting chlorinated hydrocarbon products and recovering the chlorinated hydrocarbon products from the effluent as the products of the process; wherein:

a. the alkali metal chloride is selected from the group consisting of sodium chloride, potassium chloride, a mixture thereof, a mixture of sodium chloride and no more than 20 mole peprcent lithium chloride, a mixture of potassium chloride and no more than 20 mole percent lithium chloride, and a mixture of sodium chloride, potassium chloride and no more than 20 mole percent lithium chloride;

b. the mole ratio of alkali metal chloride to iron chloride is from about 0.521 to about 2:1; and

c. 60-90 mole percent of the iron chloride is maintained as ferric chloride.

2. A process in accordance with claim 1 wherein the melt also contains a member of the group consisting of Fe O FeOCl, alkali metal fluorides, and mixtures thereof.

3. The process ofclaim 1 wherein the melt is regenerated with a combination of an oxygen-containing gas and hydrogen chloride. 

1. A CHLORINATION PROCESS CONSISTING ESSENTIALLY OF CHLORINATING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF ETHYLENE, ETHYLENE DICHLORIDE, VINYL CHLORIDE AND MIXTURES THEREOF TO PRODUCE A CHLORINATED PRODUCT WHICH CONTAINS AT LEAST 50 MOLE PERCENT OF DICHLOROETHYLENE, IN A REACTION ZONE, WHICH IS ESSENTIALLY FREE OF ELEMENTAL CHLORINE AT A TEMPERATURE WHEREIN THE RANGE OF FROM 200*-450*C, BY MEANS OF A MELT COMPRISING IRON CHLORIDE AND ALKALI METAL CHLORIDE BY DISPERSING THE MATERIAL TO BE CHLORINATED IN THE MELT, THE MELT BEING THE CONTINUOUS PHASE, WHEREBY SAID MATERIAL IS CHLORINATED BY THE MELT, WITHDRAWING A GASEOUS EFFLUENT FROM THE REACTION ZONE WHICH CONTAINS UNREACTED STARTING MATERIAL AND THE RESULTING CHLORINATED HYDROCARBON PRODUCTS AND RECOVERING THE CHLORINATED HYDROCARBON PRODUCTS FROM THE EFFLUENT AS THE PRODUCTS OF THE PROCESS, WHEREIN: A. THE ALKALI METAL CHLORIDE IS SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE, POTASSIUM CHLORIDE, A MIXTURE THEREOF, A MIXTURE OF SODIUM CHLORIDE AND NO MORE THAN 20 MOLE PEPRECTNT LITHIUM CHLORIDE, A MIXTURE OF POTASSIUM CHLORIDE AND NO MORE THAN 20 MOLE PERCENT LITHIUM CHLORIDE, AND A MIXTURE OF SODIUM CHLORIDE, POTASSIUM CHLORIDE AND NO MORE THAN 20 MOLE PERCENT LITHIUM CHLORIDE, B. THE MOLE RATIO OF ALKALI METAL CHLORIDE TO IRON CHLORIDE IS FROM ABOUT 0.5:1 TO ABOUT 2:1, AND C. 60-90 MOLE PERCENT OF THE IRON CHLORIDE IS MAINTAINED AS FERRIC CHLORIDE.
 2. A process in accordance with claim 1 wherein the melt also contains a member of the group consisting of Fe2O3, FeOCl, alkali metal fluorides, and mixtures thereof.
 3. The process of claim 1 wherein the melt is regenerated with a combination of an oxygen-containing gas and hydrogen chloride. 